A conventional single-sided color photographic paper can be subjected to exposure on only one side to form a single-sided image, and no image can be formed on the reverse side. Thus, after the photographic paper is placed in a frame or an album, it can be viewed from the only one side on which the image is formed. Consequently, the applications of the photographic paper in the field of image carrier are restrained. Besides, a supporting substrate presented in the photographic paper does not get its full use, resulting in a high cost. In recent years, short-run is digital double-sided printing technology has been developed, and the market capacity thereof has been expanding rapidly. The dominant forms of the short-run digital double-sided printings are digital printing or ink-jet printing, and they can, on a limited plane carrier, provide consumers with twice as much as the graphic information provided by a conventional single-sided photosensitive color photographic paper. Therefore, the short-run digital double-sided printing has been widely used in applications such as business cards, personalized calendars, menus, brochures for an auction, specimen cards for a hotel, invitation cards, job cards, business promotional flyers, etc, which has brought huge losses and serious challenges to the traditional silver halide printing industry. However, despite that the short-run digital double-sided printing improves efficiency to a certain extent and meets the needs of individual consumer, it has shortcomings, including limited colors, narrow color gamut, poor image-gradation, poor resolution, long delivery cycle and high cost.
Chinese utility model patent No. ZL 200520023024.5 discloses a double-sided laser exposing enlarger and a double-sided photosensitive paper used thereby. The double-sided exposing enlarger comprises an exposing unit wherein two laser exposures are installed symmetrically on the upper and lower sides of the area where the photosensitive paper is to be exposed. A circuit control unit outputs scanning signals, and under the control of these scanning signals, both sides of the photosensitive paper are exposed by the laser exposures to form an image on each side. The exposed photosensitive paper is subsequently sent to a developing unit to be developed and enlarged. Through such a process, images are formed on both sides of the photosensitive paper. The photosensitive paper disclosed in No. ZL 200520023024.5 comprises a paper base, a first photosensitive layer, a first protective layer, a second photosensitive layer and a second protective layer, wherein the first photosensitive layer and the first protective layer are successively stacked on one side of the paper base, and the second photosensitive layer and the second protective layer are successively stacked on the other side of the paper base. With respect to and toward the paper base, the first photosensitive layer and the first protective layer are configured symmetrically with the second photosensitive layer and the second protective layer, respectively. The photosensitive layers and the protective layers are stacked by a well-known conventional method for producing color photographic paper. The photographic performance of the photosensitive papers thus produced is liable to be deteriorated due to the double-sided exposure, and such defects as an increased fog density and a decreased sensitivity would occur.